SEWER SMELL

We are having the same sewer smell issue without running any roof fans or stove fan. We are also having water coming out of the vent under the bathroom sink. Water will come from there using dryer only mode on our washer/dryer combo, about 30 minutes after showering, washing dishes. Probably a tablespoon or so of water comes out no matter how much water I am using. Any suggestions for this? I was wondering what would happen if I duck tape that vent closed?

Thanks to everyone for your input. I'm going to try the remidies suggested & I'll get back to you to tell you the out come.

Larry-P

Funny you have this issue. I had/have this issue on a new 2014 Lifestyle and on my previous 2011 Cameo.
On the Cameo, the problem was solved when I did as MtPockets1 suggested by checking the tank vent cap on the roof. Carriage and Lifestyle both use only one vent on the roof as the black and gray tank pipe is "Y'ed" together so there is only one hole cut into the roof.
On the Cameo the vent pipe did not extend up through the roof fully so odors were getting into the ceiling. Once I extended the pipe and sealed the area around it the odor stopped.
I have had the Lifestyle a year. I just got home from a 3 night trip. While using the shower prior to dumping the tanks the tank smell came from under the bathroom vanity while the kitchen exhaust fan was running. The odor was being pulled either the area under the vanity itself or through a plumbing access panel in the vanity sink compartment. In addition to the p-trap and AAV under the vanity there is also one for the shower in the basement. The odor was able to travel from either of those valves but I was not able to determine which one.
Like you, I have checked for any compromises/leaks in the tanks....notta. I replaced all the standard, gravity activated AAV's with Oatey spring loaded AAV's. That seem to help but did not totally fix the issue.
Its common for manufacturers to install the holding tank vent pipes too deeply into the tanks. So as the tanks fill, the bottom of the vent pipe becomes covered with liquid. The tank then has no place in which to get air. The pressure created as more liquid is added to the tank causes the tank to burb the air someplace. It is normal the sink trap or the AAV.
So I checked the installed depth of the vent pipe for both tanks. They were not as bad as I would have expected but still about 1.5 inch deeper then needed to be. So I cut them off and reinstalled the vent pipes.
I thought I had fixed my issue as I did not smell anything on a 4 night trip back in January and the tanks got full. This week was only a 3 night trip and they did not reach the full mark but 2/3. So I'm back to square one.
Hopefully, my experience will give you some insight to help resolve your issue better then it has mine. My odor is NOT being drawn in from the roof....it comes from the basement and is obviously from the AAV's. But since I've replaced them and shortened the vent pipe so insure they are not submersed, I don't know what to do.
As others read your request for help, I would appreciate their input on my situation, too, given all that I have done. I'm certainly not hijacking your thread....I'm sure you are no the only one with this issues. Hopefully, others that have had this issue can shed some light on it for both us as well as others. Thanks! Phillip

Had a similar problem in our previous rv, turned out to be that the sewer stack was close to the bedroom roof vent and the fan was powerful enough to draw the smell back into the fiver from it when both vents were open at the same time and the fan was on full blast.

We had that smell under the same conditions you described. Our problem was resolved finally when I sealed the gap where the vent pipe exits the roof. Remove the vent cap and you'll see a gap between the pipe and where the hole was cut through the roof. Gasses were flowing back through this gap into the RV. I also sealed the gap where the dryer vent goes thru the ceiling. Our odor was from the roof vent gasses getting back inside thru those gaps... No odors since.

When you mention the "air valve"....are you referring to the air admittance valve that is located under the sinks? This is typically the major source of sewer smell, but if you have changed them, then your problem is probably a bad seal someplace.

Are you sure you have "p-traps"? Some rv's are now equipped with the duck bill in place of the normal p-trap and they will sometime get something lodged in them that will allow the odors to come back up the drains.

Another possibility is that when you run your fans, they will suck back in odors that are being sent up the tank vents located on top of the rv. Check and see how close the vents are to the fans.

Hope this helps

Ron

What can happen with open gray tank valves, the sewer gases can go up through your tanks and up the stacks. Don't know if this is your problem but you can try to create a P trap in your sewer hose. Throw a log or something under it to create a trap for the water.